Add ObjC API for getting native histograms.

webrtc/sdk/BUILD.gn

Index: webrtc/sdk/BUILD.gn
diff --git a/webrtc/sdk/BUILD.gn b/webrtc/sdk/BUILD.gn
index f4975f22938ccd563e89b8a044192f6ee010a938..8f0bb8369dcbc56334a957013925bfba5dfbc310 100644
--- a/webrtc/sdk/BUILD.gn
+++ b/webrtc/sdk/BUILD.gn
@@ -36,12 +36,17 @@ if (is_ios || (is_mac && mac_deployment_target == "10.7")) {
       "objc/Framework/Classes/RTCDispatcher.m",
       "objc/Framework/Classes/RTCFieldTrials.mm",
       "objc/Framework/Classes/RTCLogging.mm",
+      "objc/Framework/Classes/RTCMetrics.mm",
+      "objc/Framework/Classes/RTCMetricsSampleInfo+Private.h",
+      "objc/Framework/Classes/RTCMetricsSampleInfo.mm",
       "objc/Framework/Classes/RTCSSLAdapter.mm",
       "objc/Framework/Classes/RTCTracing.mm",
       "objc/Framework/Headers/WebRTC/RTCDispatcher.h",
       "objc/Framework/Headers/WebRTC/RTCFieldTrials.h",
       "objc/Framework/Headers/WebRTC/RTCLogging.h",
       "objc/Framework/Headers/WebRTC/RTCMacros.h",
+      "objc/Framework/Headers/WebRTC/RTCMetrics.h",
+      "objc/Framework/Headers/WebRTC/RTCMetricsSampleInfo.h",
       "objc/Framework/Headers/WebRTC/RTCSSLAdapter.h",
       "objc/Framework/Headers/WebRTC/RTCTracing.h",
     ]